As a method for producing nickel metal using a hydrometallurgical process, for example, there is mentioned a method described in Patent Document 1. Specifically, Patent Document 1 discloses a method in which a treatment of dissolving a raw material containing nickel in a sulfuric acid solution to remove impurities contained in the raw material is performed, ammonia is then added to a nickel sulfate solution from which impurities are separated to form nickel in the form of an ammine complex, this nickel sulfate ammine complex solution is then put in a container, the container is put under a high temperature and a high pressure, and hydrogen gas is blown to the container to reduce nickel ions in the solution, thereby producing nickel powder.
Such a method is an efficient method for obtaining high-quality nickel metal with a compact facility; on the other hand, in a case where the method is performed on an industrial scale, a problem such as durability of the facility is significant.
That is, at the time of industrial execution, when the aforementioned treatment is performed, it is necessary to continuously perform charging of the raw material into a pressurized container and extracting of a reaction product from the pressurized container; however, since a difference in pressure between the reaction container and the outside thereof is extremely large, a flow velocity of a slurry exceeds a velocity of sound at a portion of an extracting port of the reaction container. As a result, a problem arises in that abrasion of the facility caused by a contact between a slurry containing nickel powder to be discharged and the reaction container becomes severe and impact force when the nickel powder collides against the facility after the nickel powder being discharged is large, so that durability of the facility is degraded.
In particular, when coarse nickel powder generated in the pressurized container is handled, for example, a valve of controlling a discharge port is clogged by the nickel powder, and thus there is a concern that opening and closing of the valve cannot be controlled, so that this may also affect operation stability.
A material, which can withstand such abrasion or impact and is suitable for industrial utilization, has not been found yet, maintenance and repair that the facility is frequently stopped for replacing components are necessary, so that a problem such as degradation in productivity due to an increase in cost for maintenance and repair and an increase in repair time arises.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2015-212411